We're using MessagePack 0.6.6 for Java in Grails 2.0 on WebLogic 11g (10.3) to serialize string data...
public void serialize(Object object, OutputStream outputStream)
throws IOException {
byte[] bytes = MessagePack.pack(object);
outputStream.write(bytes);
outputStream.flush();
}
The problem we're seeing in WebLogic is lots of STUCK threads, so we dumped the thread stack and found some threads getting stuck at org.msgpack.template.TemplateRegistry.lookup(TemplateRegistry:198), see dump below. We're confident our code did not introduce this issue since, in the example above, it's clear we're using MessagePack.pack() in a thread-safe manner. Looking at TemplateRegistry.java, line 198, lookup() is synchronized, but we're not sure why it's causing stuck threads.
"[STUCK] ExecuteThread:
'1' for queue: 'weblogic.kernel.Default (self-tuning)'" id=43 idx=0xec tid=60 prio=1 alive, in native, blocked, daemon
-- Blocked trying to get lock: org/msgpack/template/TemplateRegistry@0xfffffffe8c2fb8e8[fat lock]
at jrockit/vm/Threads.waitForUnblockSignal()V(Native Method)
at jrockit/vm/Locks.fatLockBlockOrSpin(Locks.java:1679)[optimized]
at jrockit/vm/Locks.lockFat(Locks.java:1780)[optimized]
at jrockit/vm/Locks.monitorEnterSecondStageHard(Locks.java:1312)[optimized]
at jrockit/vm/Locks.monitorEnterSecondStage(Locks.java:1259)[optimized]
at jrockit/vm/Locks.monitorEnter(Locks.java:2466)[inlined]
at jrockit/vm/Locks.monitorEnterForced(Locks.java:859)[optimized]
at jrockit/vm/RNI.c2java(JJJJJ)V(Native Method)
at jrockit/vm/Locks.monitorEnterUnmatched(Ljava/lang/Object;)V(Native Method)
at org/msgpack/template/TemplateRegistry.lookup(TemplateRegistry.java:198)[optimized]
at org/msgpack/MessagePack.write(MessagePack.java:195)[inlined]
at org/msgpack/MessagePack.pack(MessagePack.java:639)[inlined]
You should use packer and unpacker as this blog says.
MessagePack msgpack = new MessagePack(); // singleton
Packer packer = msgpack.createPacker(outputStream); // createPacker every time
packer.write(object);
Following code may yield a perm gen memory error if you do too many since new MessagePack() loads classes every time.
MessagePack msgpack = new MessagePack();
byte[] bytes = msgpack.write(object);